Wire coiling machine particularly for producing coiled filaments for electric lamps and electronic tubes



Jan. 11, 1949. H. MARTER 2,458,789

WIRE COILING MACHINE PARTICULARLY FOR PRODUCING COILED FILAMENTS FORELECTRIC LAMPS AND ELECTRONIC TUBES Filed April 18, 1947 INVENTOR HANSMA RTER a .BY ATT'Y Patented Jan. 11, 1949 WIRE COILING MACHINEPARTICULARLY FOR PRODUCING COIDED IFILAMENT S FOR ELECTRIC LAMPS ANDTUBES ELECTRONIC Hans Martel, Milan, Italy,-assignor to SocietaTecnica-Applicazioni Metall-i Duri Ed Affini S. T. A. M. A., Milan,Italy, a corporationof Italy Application April 18, 1947., Serial 'No.742,276 :Inltaly May 18, 1946 '7 Claims. 1

This invention relates to wire coiling machines, particularly tomachines for producing helical filaments for electric lamps orelectronic tubes, and has for its main. object to devise machines whichsecure more uniformly wound products than the coiling machinesheretofore available.

This and more specific objects of the invention, as well as the novelmeans provided by the invention, are hereinafter elucidated withreference to the drawing, in which:

Figure 1 shows schematically a wire coiling machine of the general typeto which the invention may beapplied, and

Fig. 2 shows in detail the essential portion of a machine embodying theinvention proper.

According to Fig. 1, a horizontal hollow spindle 2 is journalled in ballbearings 3 and rapidly driven from an electromotor 4 by a belt 5 (2,000to 3,000 R. P. M.). The mandrel wire H of iron or molybdenum passes.from a suitably braked supply reel I, at low speed (a few millimetersper second), through the spindle bore and, on leaving the discharge endof the spindle 2, is surrounded by the filament wire l2 of tungstenwhich passes from a winding head 6 over a guide roller to be coiled uponthe mandrel. The-winding head 6 is removable from the spindle 2 andentrained by friction. Disposed near the discharge end of the spindle '2is an exchangeable mandrel feed member or capstan l. The capstan isslowly driven through gears B, 9 from the spindle'Z'. The rough capstansurface is surrounded by one or more turns of the mandrel H in order touniformly advance the mandrel by friction. The travelling mandrel isengaged by auxiliary guide rollers I3, l4 and passes from the capstan 1onto a take-up reel Ill. The machine, as a rule, is equipped withaccessory devices, such as a heating device for the tungsten wire, whichare not essential in connection with the invention and hence notillustrated.

Machines of this kind have some deficiencies Whose detriments increasewith smaller diameters of the wire to be coiled.

A calculation of the pull, normally imposed on the mandrel H between thebraked supply reel l and the capstan I, shows that the elasticelongation of the mandrel, only along its working length between thespindle discharge end and the capstan,'mayreach. an order of magnitudeequivalent z to about ten times the normal distance between twoconsecutive turns of the filament helix. It follows, thatanypermanent,periodic, or accidental variation in mandrel pull must result in acorresponding change in pitch of the wire coil Wound upon the mandrel.

This detrimental effect can be obviated only by reducing the distance ofthe capstan from the spindle end to the minimum. This, however, has beenimpossible because of the guide'roller I4 which, in the known machines,is necessary to prevent the mandrel from being bent at the spindle endwhen using capstans of different respective diameters to producefilament coils of differentgeometric characteristics.

According to the invention, in order to overcome thejust-mentioneddeficiency, the distance between spindle end and capstan is reduced t0 aminimum. by having the mandrel pass directly from the-spindle end to thecapstan, i. e. excluding' any such intermediate guiding means as theroller H! in Fig. 1, and mounting the spindle so that it can betiltedabout a stationary pivot axis parallel to that of the capstan.

Bymeans of the tiltable spindle, the direction in which the mandrelleaves the spindle and runs onto the capstan can readily be adapted tothe different diameters of the exchangeable respective capstan members;.v and exhibiting means may be provided for indicating ona scale theproper angular adjustment of the spindle for each of the customarydiameters of an available set of capstan members.

Although the angular displacements of the spindle-necessaryfor'adjusting it to the different capstan'd'iameters, are relativelyvery small, a conventional belt transmission between drivemotor'and'spindl'e is apt to show the known drawbacks of suchtransmissions to an increased extent. Therefore, according-to anotherfeature of the invention, the. tiltable spindle is directly drivenbyanelectromotor whose armature is mounted on the spindle, preferably sothat any intermediate coupling devices are avoided and the spindlerepresents a part or an extension of the motor shaft.

-Wi'th atiltably mounted spindle, special care must be taken to preventdeficiencies of the wire coilduetoaxialdisplacementsofthe spindle. Evenwith non-tiltable-spindles journalledin highest- 3 quality ballbearings, slight axial displacements and ensuing vibrations cannot befully prevented at the high revolving speeds of the spindle. Any

such axial displacement of the spindle causes a correspondingdisplacement of the point at which the tungsten wire, coming from thewinding head, runs onto the mandrel and hence results in a correspondingerror in the pitch of the helix. Such errors, in view of the very smallpitch of the helices, may assume high relative values. With a tiltablespindle, the possibility of axial spindle displacements is increasedbecause the pivot points of the spindle lie away from the spindle sothat vibratory forces may act with an increased leverage.

According to another feature of the invention, however, the occurrenceof pitch errors of the helix due to axial displacements of the spindleis avoided by assigning the guidance of the mandrel within the spindleto a separate guiding tube. This tube is inserted in the bore of thespindle and fastened so that it tilts together with the spindle but isprevented from following its revolving and possible axial movements.

The above-mentioned features and other details of machines according tothe invention are apparent from the embodiment exemplified by Fig. 2.Fig. 2 is limited to showing the portion of a wire coiling machineessential from the viewpoints of the present invention, and thereference numerals in Fig. 2 are identical with those used in Fig. l forthe corresponding respective elements.

According to Fig. 2, a mounting or base plate 25 carries all illustratedparts including a vertical hollow spindle 2 whose upper portion carriesthe armature of an electric motor 4. The roller bearings 3 for thespindle are mounted on a plate structure 2? whose portion 21a is pivotedabout a shaft 28. Another portion 21b of structure 27 carries a pointer29 for indicating on a scale 38 the proper angular adjustment of thespindle 2. The adjustment is carried out, for instance, by a hand wheel3| through Worm gears l6 and i8. After completing the adjustment, theplate 2? is securely fastened in posi tion by tightening a hand screw 19which passes through a slot 20 in portion 21b of plate 21. A worm 8firmly mounted on spindle 2 between the bearings 3 meshes with a Wormgear 9 whose shaft 28 carries a pinion 33 on the other side of baseplate 25. A large spur gear 34 meshes with pinion 33. The shaft 35 ofgear 34 extends to the front side of base plate 25 and carries anexchangeable mandrel feeding member or capstan in proximity of the lowerend (discharge end) of the spindle. A winding head 36 with the supplyreel t for the tungsten wire 92 is placed on the lower end of spindle 2to be entrained by friction. Guiding nozzles or rollers for the tungstenwire are denoted by 24. A tube is loosely inserted in the bore of thespindle, the projecting upper and lower ends of the tube being visiblein Fig. 2 and denoted by 2|. The mandrel wire it is guided through thetube 21. At its upper end, the tube 2| is firmly clamped betweenclamping checks 22 tightened by a hand screw 23. Thus, the tube isprevented from partaking in the revolving movement of the spindle. Asmall hand wheel 3'! at the upper end of spindle 2 permits revolving itmanually. The lower end of tube 2| is designed as an exchangeable nozzleto permit adapting the nozzle opening to different mandrel diameters andreplacing worn nozzles Without having to replace the entire tube 2|.

During the operation of the machine, the mandrel ll moves slowly from asupply reel (not shown in Fig. 2) over several guide rollers, of whichonly one is shown at 26, to the upper end of the guiding tube 2| andthrough the tube. Immediately below the discharge end of the tube, thetungsten wire I2 is coiled upon the mandrel, before the mandrelsurrounds the capstan I with one or more turns and travels, with thetungsten coil upon it, onto a take-up reel (not shown in Fig. 2).

If the geometric characteristics of the filament coil are to be changed,another capstan member of the corresponding diameter is placed on shaft35, and the direction of mandrel wire as it leaves the spindle tube 2|is adapted to the new capstan diameter by tilting the spindle to acorresponding angular position shown on the scale 30. The absence of anyguiding device between the spindle end and the capstan 1 permitsreducing their mutual distance to a minimum so that the abovementioneddrawbacks of the known machines are eliminated.

It will be apparent from the foregoing that by irtue of a tiltablemandrel guide spindle according to the invention, preferably incombination with a direct electric drive whose motor armature is mountedon the spindle and preferably with an inserted guiding tube, aconsiderable improvement in design and functioning is achieved with theresult that the filament coils have a larger degree of uniformity andinclude a reduced amount of rejects as compared with the machinesheretofore available.

I claim:

1. A wire coiling machine, comprising a hollow mandrel-guide spindlerevolvable about its axis, a winding head disposed on said spindle nearits discharge end for accommodating the wire to be coiled, a mandrelfeeding member disposed near said spindle end and revolvable about anaxis extending at an angle to an axial plane of said spindle, saidspindle being angularly displaceable about a stationary pivot axisextending parallel to said axis of said feeding member.

2. A wire coiling machine, comprising a hollow mandrel-guide spindlerevolvable about its axis, a winding head disposed on said spindle nearits discharge end for accommodating the wire to be coiled, a revolvablemandrel-feeding member disposed in front of said spindle end and havingan axis of revolution extending at a right angle to an axial plane ofsaid spindle, a structure having hearings in which said spindle isrevolvable and having a stationary pivot whose axis is parallel to thatof said member.

3. A wire-coiling machine, comprising a hollow mandrel-guide spindlerevolvable about its axis, drive means for said spindle, a winding headplaced on said spindle near its discharge end for accommodating the wireto be coiled, a mandrel feeding member disposed near said spindle endand revolvable about an axis extending substantially at aright angle toan axial plane of said spindle, gear means coupling said spindle withsaid member for driving the latter and having a gear member whose axisis parallel to that of said member, and a structure having bearings forsaid shaft and being pivotally movable about said gear memberaxis topermit angularly displacing said spindle.

4. A wire-coiling machine, comprising a hollow mandrel-guide spindlerevolvable about its axis, anelectromotor having an armature mounted onsaid spindle for driving the latter, a winding head, placed on saidspindle near its discharge end for accommodating the wire to be coiled,a mandrel capstan in front of said spindle end for pulling the mandrelthrough said spindle, and gear means connecting said capstan with saidspindle.

5. In a machine according to claim 4, said gear means having a gearmember driven from said spindle and rotatable about a stationary axis,and a structure carrying said motor and spindle and being pivotallymovable about said stationary axis.

6. A machine according to claim 1, comprising a tube disposed in thehollow of said spindle to be traversed by the mandrel, and fasteningmeans disposed at the other end of said spindle and engaging said tubeso from revolving while permitting it to participate in angulardisplacements of said spindle.

7. A machine according to claim 2, comprising as to prevent said tube-REFERENCES CITED The following references are of record in the fiieofthis patent:

UNITED. STATES PATENTS Number Name Date 1,227,659 Quackenbush et a1. May29, 1917 1,338,498 Eisler Apr. 27, 1920 1,667,677 Reufel et a1 Apr. 24,1928 1,667,681 Shepherd et a1. Apr. 24, 1923

